EP2580564B1 - Pressure sensor with a cylindrical pressure measurement cell - Google Patents

Description

The present invention relates to a pressure transducer with a cylindrical pressure measuring cell. Generic pressure transducers have a ceramic pressure measuring cell in a housing, wherein the pressure measuring cell is arranged in a measuring cell chamber in the housing, wherein the measuring cell chamber has an opening through which the pressure measuring cell can be acted upon with a media pressure, wherein the housing has a radially inwardly extending annular shoulder has, which surrounds the housing opening, and which forms an axial stop surface for a sealing ring, on which rests a sealing ring, against which the pressure measuring cell is clamped axially with a self-tensioning device. For positioning the pressure measuring cell and the sealing ring in the housing angular rings are used, which are inserted in an annular gap between the lateral surface of the pressure measuring cell and the housing wall, and which surround the edge of the opening-side end face of the pressure measuring cell. A generic pressure transducer is for example in the European patent EP 0 594 808 B1 discloses, wherein the angle ring described therein in particular serves to enable a modular construction of the housing, wherein the axial shoulder is formed on a process connection body having the housing opening through which the pressure measuring cell is to be acted upon with a pressure, wherein the connection body its lateral surface has a thread, which engages in a complementary internal thread in the housing, wherein the internal thread is arranged in a front end portion of the sensor chamber. The task of the angle ring is in this context two things, namely on the one hand, the axial and radial positioning of the pressure measuring cell in the housing and on the other hand holding the O-ring before mounting the connector body. However, in particular the voltage behavior of the pressure measuring cell in the housing is sufficient elastic material for the angle ring ahead, which requires compromise with respect to the radial support of the sealing ring by the angle ring, since the sealing ring and angle ring materials have similar hardness, and insofar as the angle ring hardly seems suitable for supporting the sealing ring under pressure load.

The publication EP 1 942 525 A1 discloses a sealing device for closing a pressure measuring cell housing on a rear side facing the housing of a pressure measuring cell, wherein the sealing device comprises a pressure equalization opening for a pressure equalization line of the pressure measuring cell housing recorded pressure measuring cell, wherein the sealing means of a dimensionally stable hard part with at least one in the region of the pressure equalization opening attached to the hard part elastic Soft part is formed.

The publication WO 2010 046 249 A1 discloses a pressure transducer having an elongated housing, a pressure measuring cell arranged in the housing, wherein the housing has at least one opening through which the sensor can be acted upon by a pressure, the pressure measuring cell is axially clamped in the housing against a seal.

The publication DE 101 33 066 A1 discloses a pressure measuring cell which is enclosed in a sleeve having a radially inwardly extending shoulder on which rests the pressure measuring cell, wherein between the shoulder and the edge of the pressure measuring cell, a centering ring with a cylindrical portion and an integrally formed thereon extending radially inwardly Shoulder is arranged. The centering ring causes a soft and low-tension bearing of the pressure cell. In addition, the centering ring causes a seal of the gap between the pressure measuring cell and the sleeve.

For smaller pressure cells, however, it is necessary to precisely define the position of the sealing ring, since the relative importance of a radial displacement of the sealing ring wins with decreasing diameter of the pressure measuring cell in importance. It is therefore an object of the present invention to provide a pressure transducer, which overcomes the disadvantages of the prior art, so on the one hand, the pressure measuring cell stored stress-free in the measuring cell chamber and on the other hand, the sealing ring positioned radially defined under pressure load. The object is achieved by the pressure transducer according to the independent claim. 1

The pressure measuring transducer according to the invention comprises: a substantially cylindrical pressure measuring cell, a measuring cell housing with an at least partially substantially cylindrical measuring cell chamber; a sealing ring; a jig; and an angle ring for positioning the pressure measuring cell and the sealing ring in the measuring cell chamber, wherein the measuring cell chamber has an opening through which the measuring cell chamber can be acted upon by a media pressure, wherein the measuring cell housing has an annular axial stop surface which surrounds the opening, and which of a cylindrical wall of the measuring cell chamber extends radially inwardly, wherein the sealing ring rests on the axial stop surface, wherein the pressure measuring cell rests with a front end face on the sealing ring, wherein the clamping device rests on a rear end face of the pressure measuring cell to the pressure measuring cell against the sealing ring clamped axially, wherein the angle ring is disposed in an annular gap between the pressure measuring cell and a wall of the measuring cell chamber and having a radially inwardly extending shoulder which surrounds an edge region of the front end face of the pressure measuring cell, wherein the radial shoulder defines a radial stop to the sealing ring to position between the pressure measuring cell and the axial abutment surface, wherein according to the invention the angle ring comprises at least a first component having a dimensionally stable material, and at least one second component having an elastic material, wherein the at least one dimensionally rigid component forms the radial shoulder and extends in the axial direction in the annular gap, wherein the second component is connected to the first component and extending in the annular gap at least partially radially between the lateral surface of the pressure measuring cell and the wall of the measuring cell chamber to position the pressure cell with respect to the measuring cell chamber, the cylindrical portion having one or more apertures through which the second component extends to connect the second component to the first component.

In a development of the invention, the first component has a substantially cylindrical section, from which the radial shoulder extends radially inwards at one end section.

In one embodiment of the invention, the apertures comprise bores or axial slots in the cylindrical portion.

In one development of the invention, the second component comprises an elastomer having a hardness of not more than 50 Shore A. The elastomer may in particular comprise VMQ or EPDM.

In a development of the invention, the first component comprises an organic material, in particular an elastomer. The polymer of the first component may in particular comprise PEEK, PS or PA xx, in particular PA 6, PA 66, PA 12, PA MACM 12, PA 6-3-T.

The pressure measuring cell may in particular be a ceramic pressure measuring cell, which has a base body and a measuring membrane, wherein the measuring membrane is pressure-tightly connected to the base body along its edge by means of an annular joint, wherein the sealing ring rests on the measuring membrane in the area of the measuring membrane which is aligned with the joint , The sealing ring may in particular comprise an elastomer.

The clamping device may comprise a threaded ring according to a development of the invention, which has a thread on its lateral surface, and wherein the housing has a complementary to the thread of the screw inner thread into which the screw ring is screwed to clamp the pressure measuring cell.

According to one embodiment of the invention, at least one decoupling body is arranged between the screw ring and the pressure measuring cell. The decoupling body is used in particular to radial stresses due to different thermal expansion coefficients of the material of the screw ring on the one hand and the material of the pressure measuring cell on the other hand, de could be introduced via frictional engagement in the pressure measuring cell, keep away from the pressure measuring cell.

In a currently preferred embodiment of the invention, the decoupling body has the same material as the pressure measuring cell or as the main body of the pressure measuring cell.

According to one embodiment of the invention, the second component of the angle ring comprises a plurality of spring elements which are arranged in the annular gap for positioning the pressure measuring cell.

In a further development of the invention, the cylindrical section of the first element does not fill more than 70%, preferably not more than 50%, of the volume of the annular gap between the pressure measuring cell and the wall of the measuring cell chamber, the spring elements not exceeding 80%, preferably not more than 60% and more preferably not more than 50% of the remaining volume of the annular gap fill. The remaining volume of the annular gap is the difference between the total volume of the annular gap and the volume of the cylindrical portion of the first element in the annular gap.

The spring elements comprise in one embodiment of the invention, webs which extend in the axial direction.

In one embodiment of the invention, the radial stop for the sealing ring has a toroidal contact surface for the sealing ring.

By controlling the lateral position of the pressure measuring cell, the angle ring further serves the purpose of ensuring the dielectric strength of, for example, 600 V between the circuit ground of the pressure measuring cell and the mass of the housing (ground). In particular, a metallic joint between the measuring diaphragm and the base body of the pressure measuring cell, which extends up to the lateral surface of the pressure measuring cell, is placed on circuit ground of the pressure measuring cell. So far It is important to observe the minimum distances between the lateral surface of the pressure cell and the housing, which is achieved by the angle ring.

Fig. 1:

einen Längsschnitt durch einen Abschnitt eines erfindungsgemäßen Druckmessaufnehmers;

Fig. 2:

ein Ausführungsbeispiel eines Winkelrings eines erfindungsgemäßen Druckmessaufnehmers;

Fig. 3:

die erste Komponente des Winkelrings aus Fig. 2; und

Fig. 4:

die zweite Komponente des Winkelrings aus Fig. 2.

The invention will now be explained with reference to the embodiments shown in FIGS. It shows:

Fig. 1:

a longitudinal section through a portion of a pressure measuring transducer according to the invention;

Fig. 2:

an embodiment of an angle ring of a pressure measuring transducer according to the invention;

3:

the first component of the angle ring Fig. 2 ; and

4:

the second component of the angle ring Fig. 2 ,

The in Fig. 1 shown pressure measuring transducer 1 comprises a pressure measuring cell 2, which has a cylindrical base body 3 and a measuring diaphragm 4, wherein the measuring diaphragm is connected to the main body along a circumferential annular joint 5 pressure-tight. The measuring membrane and the base body preferably have a ceramic material, in particular corundum, wherein the joint may comprise, for example, an active brazing material, in particular a Zr-Ni-Ti active brazing material or glass.

The pressure measuring cell is arranged in a housing 6, which has in its interior a cylindrical measuring cell chamber 7, which is acted upon by a frontal opening 8 with a pressure, wherein the frontal opening 8 is bounded by a radial shoulder 9, which extends from the cylindrical wall the measuring cell chamber 7 extends radially inwardly. The radial shoulder 9 defines an axial stop 10 on which an elastic sealing ring, in particular an O-ring 11 is supported. The pressure measuring cell 2 is between the sealing ring 11 and a Clamping ring 12 axially clamped in the measuring cell chamber, wherein the clamping ring 12 has a male thread 13 on a portion of its lateral surface, which rests in a complementary internal thread 14 in the housing 6. Between the clamping ring 12 and the pressure measuring cell, a decoupling ring 15 is arranged and clamped, wherein the decoupling ring 15 in particular has the same material as the main body of the basic measuring cell 2. For positioning the pressure measuring cell 2 in the measuring cell chamber 7, an angle ring 20 is provided which has a cylindrical portion 21 and a radial shoulder 22, wherein extends radially inwardly through the radial shoulder 22 at an end face of the cylindrical portion 21. The angle ring is arranged in an annular gap, which is formed between the pressure measuring cell 2 and the wall of the measuring cell chamber 7, wherein the angle ring with its radial shoulder 22 surrounds the edge region of the measuring diaphragm 4. The radial shoulder 22 has a contact surface 24, on which the sealing ring 11 is radially supported. The angle ring 20 comprises a first component 26, which has a substantially dimensionally stable elastomer under the forces occurring, and a second component 28, which has a much softer elastomer, wherein the first component forms a basic structure of an angle ring to which secures the second component is.

The radial shoulder 22 serves to support the sealing ring, wherein the radial shoulder extends between the contact surface 24 for the sealing ring 11 and a lateral surface portion 32 of the first component, wherein the lateral surface portion is positioned in clearance in the housing and thus the position of the sealing ring with respect to the Housing sufficiently well defined, wherein the sealing ring is radially supported in this position under pressure by the radial shoulder 22 on the contact surface 24.

wobei d₀ der Solldurchmesser ist. Die Toleranzen des Spalts betragen dementsprechend den halben Wert der Durchmessertoleranz.For the tolerance of the diameter d of the angle ring in the area of the clearance, the following applies: $${\mathrm{d}}_{\mathrm{0}}-\mathrm{0}.\mathrm{05}\mathrm{mm}<\mathrm{d}<{\mathrm{<figure-callout\; id="0"\; label="d"\; filenames="imgf0003.png"\; state="\{\{state\}\}">d</figure-callout>}}_{\mathrm{0}}+\mathrm{0}.\mathrm{15}\mathrm{mm}.$$

where d _{0 is} the nominal diameter. The tolerances of the gap are accordingly half the value of the diameter tolerance.

This in Fig. 2 illustrated embodiment of an angle ring 20 has a cylindrical portion 21 and a radial shoulder 22, wherein the angle ring has in a first component 26 on its comparatively hard elastomer and a second component 28 of a relatively soft elastomer. The first component 26 defines a cylindrical basic structure and a radial shoulder 22 up to its radial abutment surface 24, wherein the second component 28 comprises axial webs 24, which penetrate openings of the first component 26, and wherein the axial webs 34 connected to each other via a ring 36 which forms part of the radial shoulder 22.

The pressure measuring cell is inserted into this angle ring, wherein the lateral position of the pressure measuring cell in the measuring cell chamber of the housing is defined by the webs 34, wherein the webs 34 in turn abut the housing wall of the measuring cell chamber.

Fig. 3 now shows an individual view of the first component 26 of the angle ring, wherein holes 28 and 40 can be seen here, which form the openings through which the webs 34 extend in the radial direction to fix them with respect to the first component.

Fig. 4 finally shows an individual representation of the second component of the angle ring according to the invention, wherein the webs 34 are connected to each other via a circumferential ring 36. The angle ring is made by overmolding the first component in an injection molding process with the material of the second component.

As a result, the present invention discloses a pressure transducer with improved positioning of the sealing ring in the housing, which is the prerequisite for a consistent measurement accuracy in smaller measuring cells.

Claims (13)

1. Pressure sensor (1) comprising:

   an essentially cylindrical pressure measuring cell (2),

   a measuring cell housing (6) with an essentially cylindrical measuring cell chamber (7),

   wherein the measuring cell chamber has an opening through which the measuring cell chamber can be exposed to a medium pressure, wherein the measuring cell housing (6) has an annular axial stop face (10) which surrounds the opening and which extends radially inwards from a cylindrical wall of the measuring cell chamber;

   a sealing ring (11);

   a clamping device (12); and

   an angle ring (20) designed to position the pressure measuring cell (2) and the sealing ring (11) in the measuring cell chamber,

   wherein the sealing ring (11) lies on the axial stop face (10),

   wherein the pressure measuring cell (2) lies with its front abutting face on the sealing ring (11),

   wherein the clamping device (12) lies on the rear abutting face of the pressure measuring cell in order to axially clamp the pressure measuring cell against the sealing ring (11),

   wherein the angle ring (20) is arranged in an angular gap between the pressure measuring cell (2) and a wall of the measuring cell chamber (7) and features a shoulder (22) that extends radially inwards, said shoulder surrounding a marginal zone of the front abutting face of the pressure measuring cell (2),

   wherein the radial shoulder (22) defines a radial stop in order to position the sealing ring between the pressure measuring cell and the axial stop face,

   wherein the angle ring (20) comprises at least a first component (26), which features a rigid material, and at least a second component (28), which features an elastic material, wherein the at least first component forms the radial shoulder (22) and extends into the annular gap in the axial direction,

   wherein the first component (26) features an essentially cylindrical section from which the radial shoulder (22) extends radially inwards at an end section,

   wherein the second component (28) is connected to the first component and in the annular gap extends radially at least in part between the lateral surface of the pressure measuring cell (2) and the wall of the measuring cell chamber (7) in order to position the pressure measuring cell (2) in relation to the measuring cell chamber (7), characterized in that the cylindrical section features at least one or several apertures (38, 40) through which the second component extends (28) in order to connect the second component (28) with the first component (26).
2. Pressure sensor (1) as claimed in Claim 1, wherein the apertures comprise bore holes (38, 40) or axial slits in the cylindrical section.
3. Pressure sensor (1) as claimed in one of the previous claims, wherein the second component (28) features an elastomer with a hardness of no more than 50 Shore A.
4. Pressure sensor (1) as claimed in one of the previous claims, wherein the elastomer of the second component (28) features VMQ or EPDM.
5. Pressure sensor (1) as claimed in one of the previous claims, wherein the first component (26) features an organic material, particularly an elastomer, preferably PEEK, PS or PAxx.
6. Pressure sensor (1) as claimed in one of the previous claims, wherein the pressure measuring cell (2) is a ceramic pressure measuring cell which has a meter body (3) and a measuring membrane (4), wherein the measuring membrane (4) is connected pressure-tight to the meter body (2) along its edge by means of an annular joint (5), wherein the sealing ring (11) lies on the measuring membrane in the area of the measuring membrane that is flush with the joint (5).
7. Pressure sensor (1) as claimed in Claim 6, wherein the sealing ring (11) features an elastomer.
8. Pressure sensor (1) as claimed in one of the previous claims, wherein the clamping unit comprises a screwed ring which has a thread on its lateral surface, and wherein the housing features an internal thread, complementing the thread of the screwed ring, into which the screwed ring is screwed in order to clamp the pressure measuring cell.
9. Pressure sensor (1) as claimed in Claim 10, wherein at least one decoupling body is arranged between the screwed ring and the pressure measuring cell.
10. Pressure sensor (1) as claimed in one of the previous claims, wherein the second component (28) comprises several spring elements (34) which are arranged in the annular gap to position the pressure measuring cell.
11. Pressure sensor (1) as claimed in Claim 12, wherein the cylindrical section of the first component fills no more than 70%, and preferably no more than 50%, of the volume of the annular gap between the pressure measuring cell and the wall of the measuring cell chamber (7), and wherein the spring elements (34) fill no more than 80%, preferably no more than 60% and particularly preferably no more than 50% of the remaining volume of the annular gap.
12. Pressure sensor (1) as claimed in Claim 10 or 11, wherein the spring elements feature ridges (34) that extend in the axial direction.
13. Pressure sensor (1) as claimed in one of the previous claims, wherein the radial stop for the sealing ring (11) features a toroidal bearing surface for the sealing ring (11).

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